Formation of cycloheptyne-dicobalt hexacarbonyl complexes via Nicholas allylation reactions and ring closing metathesis: Intramolecular 2+2+2 and Pauson-Khand reactions on cycloheptyne complexes.
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Mechanical, Automotive, and Materials Engineering
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One of the objectives of this thesis was to reduce the formation of vinyl silane side 140a,b,c & 145 products formed in the 4+3 cycloaddition reactions. By employing allyltrimetal nucleophile 149, virtually eliminated or reduced to trace amounts these vinyl silane side products observed earlier. DIBAL reduction and in situ acetylation, followed by exposuere to BF3 afforded cycloheptenyne dicobalt complex 156a,b & 163a, bearing a allyl trimethyl silane functional group and a silyl group at beta-position. The second and major objective of my thesis was to prepare tethered alkenes or alkynes of cycloheptyne dicobalt complexes. Cyloheptyne dicobalt complexes of 187, 188, 215, and 220 bearing an acetoxy group was prepared by ring closing metathesis. These complexes were functionalized easily via Nicholas reactions in high yields. Tethered alkenes did undergo Pauson-Khand reactions with good to excellent yields furnishing 7,5,5 fused ring systems. While the tethered alkynes did undergo 2+2+2 cycloaddition reactions, giving fused 7,6,5 ring systems, with respectable yield. Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 5987. Thesis (Ph.D.)--University of Windsor (Canada), 2005.
Mohamed, Ahmed Bashir., "Formation of cycloheptyne-dicobalt hexacarbonyl complexes via Nicholas allylation reactions and ring closing metathesis: Intramolecular 2+2+2 and Pauson-Khand reactions on cycloheptyne complexes." (2005). Electronic Theses and Dissertations. 2147.